In aircraft hydraulic systems, for example, the hydraulic tubing is typically closely spaced and requires the use of wrenches to tighten typical flare nuts joining the tubing. Further, in modern aircraft the hydraulic pressure in the tubing is of the order of 3,000 pounds per square inch, the tubing being typically made of titanium. At such pressures 1800 inch/pounds of torque are required to make the flare nut joints leakproof. In the prior art, for example, on steel tubing 1200 inch/pounds of torque were required for lower hydraulic pressures and for still lower pressures, when aluminum tubing was used the torque required was 600 inch/pounds.
The tubing is typically arranged where clearance around a nut point is limited to about 0.2" for a wrench on the nut. That is, the wrench must be rotated in an arc when tightening a nut so that the distance from the points on the nut, or the points in the wrench engaging the nut, to the outer surface of the wrench is about 0.2".
Existing wrenches of the nine point or twelve point crowfoot-type have had a square drive socket located at the lower center of the jaw, and in the nine point open end wrench, the socket is opposite the open end. These jaws were typically arranged for right or left hand engagement.
These existing wrenches have presented the problems of spreading and slipping off of the nut when high torques are applied. If the jaw of the wrench was open-ended, as in a nine point wrench, at high torques the jaws typically spread so as to not be able to provide leakproof hydraulic systems. In addition when a wrench slips while high torque is being applied, there is a danger to the operator in that his arm or elbow can be severly damaged by contact with surrounding equipment as a result of sudden and uncontrolled movement of the wrench handle.
A search of the patent literature discloses a number of wrenches. For example, U.S. Pat. No. 4,130,032 to Giandomenico et al. illustrates a wrench having an open end but which has the characteristics of a closed-end wrench. The wrench includes a sleeve forming a nut-engageable socket with a gap in its side, and an adapter forming a socket with a gap in its side, the adapter closely surrounding the sleeve and extending across the gap in the sleeve. The sleeve and adapter have surfaces that become fully engaged when a wrench handle is applied to the adapter to turn it so as to tighten a nut engaged by the sleeve. This wrench has a relatively complicated structure and requires substantial clearance because the sleeve fits over the nut and within the jaw of the wrench.
The following patents disclose additional wrenches found in the search:
U.S. Ser. No. 661,011: M. D. Converse PA1 U.S. Ser. No. 1,276,071: W. L. Ringling PA1 U.S. Ser. No. 1,479,772: W. H. Cook PA1 U.S. Ser. No. 1,861,207: F. J. Burns PA1 U.S. Ser. No. 2,334,069: E. T. Collins et al. PA1 U.S. Ser. No. 2,618,996: G. T. Logan PA1 U.S. Ser. No. 3,875,828: Evans PA1 U.S. Ser. No. 4,222,293: Schrever et al. PA1 British No. 13,266: A. W. King PA1 French No. 84,427: L. Bonnhoff.